The present disclosure relates to network computing. Computer networks typically include a collection of computing devices enabled to communicate with each other for handling data traffic and control instructions. For example, such devices can include servers, data centers, routers, network switches, management applications, wireless access points, and client computers. Computer networks can provide network connectivity to wired computing devices and/or wireless computing devices.
Computer networks can include various configurations. One such configuration, known as a virtual private network (VPN), is a network that operates over a public communication network (such as the Internet) to provide remote offices or individual clients with secure, private access to a specific network, such as a network specific to an organization or company. VPNs function by encapsulating data transfers between two or more networked devices that are not on the same private network. Such encapsulation keeps transferred data private from other devices on one or more intervening local area networks or wide area networks. A VPN can enable a group of client computers to communicate and access specific resources as members of a given broadcast domain even if the various member client computers are not attached to the same network switch.
Network services, including VPN services are commonly provided using Ethernet technology. Ethernet has become a default Data Link Layer technology for data transport, that is, the default for Layer 2 (L2) of the Open Systems Interconnection (OSI) model. There are several accompanying technologies and protocols that expand Ethernet technologies to other or larger networks. One such protocol is that of Transparent Interconnect of Lots of Links (TRILL). TRILL is a technology designed to provide a transparent mechanism for carrying L2 user traffic though a transport network. TRILL uses nodes or devices, in a transport network, known as Routing Bridges (RBridges). RBridges are devices that support the TRILL specification. TRILL is currently an Internet Engineering Task Force (IETF) draft protocol, the specification of which is accessible from ietf.org (tools.ietf.org/search/draft-ietf-trill-rbridge-protocol-16).
In a TRILL topology, RBridges are separated by a transport network. The transport network could be using a variety of technologies, though Ethernet is technology is the most popular choice for the transport network. When using Ethernet transport between RBridges, forwarded packets carry a TRILL Ethernet header that includes a Media Access Control (MAC) source address (MAC-SA) and a MAC destination address (MAC-DA). A network that uses TRILL can connect customer networks directly through RBridges, or over one or more transport networks, allowing interconnection of multiple RBridges without losing each customer's individually defined Virtual LANs (VLANs). There exist other related technologies that follow a model of a transport network that connects two or more customer networks (access networks), where the transport network is functionally distinct from the customer network, even if a single administrator runs both networks.